add persistant Favorite

app/src/main/java/com/example/tdsaeandroid/MainActivity.kt

@@ -6,6 +6,7 @@ import android.widget.Button
 import android.widget.ImageButton
 import androidx.activity.enableEdgeToEdge
 import androidx.appcompat.app.AppCompatActivity
+import com.example.tdsaeandroid.favourites.FavouritesData
 
 class MainActivity : AppCompatActivity() {
 
@@ -35,6 +36,8 @@ class MainActivity : AppCompatActivity() {
         btFav.setOnClickListener {
             startFavoritesActivity()
         }
+
+        FavouritesData.init(this)
     }
 
     private fun startMediasActivity(type: ActivityType) {

app/src/main/java/com/example/tdsaeandroid/favourites/FavouritesData.kt

 package com.example.tdsaeandroid.favourites
 
+import android.content.Context
+import android.content.Context.MODE_PRIVATE
+import android.content.SharedPreferences
+import com.example.tdsaeandroid.json
 import com.example.tdsaeandroid.model.media.MediaInList
+import kotlinx.serialization.encodeToString
 
 object FavouritesData {
-    private val favorites = mutableListOf<MediaInList>()
+    private lateinit var sharedPreferences: SharedPreferences
+
+    fun init(context: Context) {
+        sharedPreferences = context.getSharedPreferences("Favourites", MODE_PRIVATE)
+        if (!sharedPreferences.contains("favourites")) {
+            write(mutableListOf())
+        }
+    }
 
     fun addFavorite(media: MediaInList) {
+        val favorites = getFavorites()
         if (!inFavorites(media)) {
             favorites.add(media)
         }
+        write(favorites)
     }
 
     fun removeFavorite(media: MediaInList) {
+        val favorites = getFavorites()
         if (inFavorites(media)) {
             favorites.remove(media)
         }
+        write(favorites)
     }
 
-    fun getFavorites(): List<MediaInList> {
-        return favorites
+    fun getFavorites(): MutableList<MediaInList> {
+        val savedName = sharedPreferences.getString("favourites", "") ?: ""
+        return json.decodeFromString(savedName)
     }
 
     fun inFavorites(media: MediaInList): Boolean {
+        val favorites = getFavorites()
         return media in favorites
     }
+
+    private fun write(favorites: List<MediaInList>) {
+        val editor = sharedPreferences.edit()
+        editor.putString("favourites", json.encodeToString(favorites))
+        editor.apply()
+    }
 }
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